Hitherto, as an indoor unit of an air-conditioning apparatus for a computer room, a unit that blows out air from a lower portion of a casing of the indoor unit is known. In general, in the indoor unit of the air-conditioning apparatus of such a downward blow-out type, with a heat exchanger being a boundary, a primary side (an upstream side in a ventilation direction) corresponds to an upper position, and a secondary side (a downstream side in the ventilation direction) corresponds to a lower position. In the indoor unit, when an air-conditioned space is cooled, dew condensation water is generated on a surface of a heat exchanger, which serves as an evaporator. Wind that passes between fins of the heat exchanger disperses the dew condensation water, and may cause the dew condensation water to leak to the outside of the unit.
As means for preventing such a dispersion of dew condensation water, a sub-drain pan is used. In the indoor unit in which the secondary side of the heat exchanger corresponds to a lower position, an operation state in which dew condensation water cannot be collected by only using a main drain pan may occur. In such a case, when the sub-drain pan is provided together with the main drain pan, dew condensation water received by the sub-drain pan can be conveyed to the main drain pan. A technology related to such an existing sub-drain pan is disclosed in, for example, Patent Literature 1 below. Patent Literature 1 describes an air-conditioning apparatus including a movable sub-drain pan. In the air-conditioning apparatus, when an operation state in which dew condensation water is not generated occurs, to reduce ventilating resistance caused by the sub-drain pan, the angle of the sub-drain pan can be changed.
On the other hand, in the indoor unit of the existing air-conditioning apparatus, to reduce production cost of the heat exchanger, there may be a case in which the heat exchanger is produced with the heat exchanger divided into an upper heat exchanger and a lower heat exchanger, and, when the heat exchanger is mounted on the indoor unit, the divided portions of the heat exchanger are connected to each other to obtain a predetermined heat exchanger capacity. In particular, a method of producing a high-capacity heat exchanger used in an indoor unit of a large air-conditioning apparatus differs from a method of producing a relatively small heat exchanger, so that production costs increases. To reduce the production costs, the above-described means is used to provide the predetermined heat exchanger capacity in the indoor unit.